Film-developing tank



Dec. 24, 1940. w, B, M OR 2,226,438

FILM-DEVELOPING TANK Filed May 28, 19158 1N VENTOR Walrer B. Moorz.

A TTORNE Y5 BY f Patented Dec. 24, 1940 I UNITED STATES PATENT OFFICE Y 1 I I 2,226,438

FILM-DEVELOPING TANK Walter B. Moore, West Lafa' ette, Ohio I Application May 2a, 1938, Serial No. 2 10.735 I 2 Claims. My invention relatesv to a film-developing tank. It has to do, moreparticularly, with a tank for developing photographic film and which is In the past, no satisfactory'tank has been'provided for developing roll film whereby it is possible to observe the films while they are in the developer in the tank so as to observe the progress and development. Also, the tanks commonly usedfor developing films are not provided with eilicient means for circulating the developer in such a manner as to eliminate all the air bubbles and thereby result in a more accurate development of the film. Prior art tanks of this general nature g i base I which may be of wood or metal or of any have also been possessed of many other defects.

One of the objects of my invention is to .pro-.-

In its preferred form, my inventioncontem- 2 plates the provision of a film-developing tank which is constructed mainly of a transparent material so that films supported therein may be seen without removing them fromthe tank. The tank is preferably vertically disposed and is preferably so disposed that theroll film may be suspended therein. Although the tank is made mainly of transparent material to permit the film to be viewed while suspended. therein, '1 prei'erablyprovide a light-tight cover which may be placed overthe tank so, that the developing may occur, ii desired, while there is light in the room where the device is located, for example, while the user is performing some other task in the room which requires the room" to be lighter. I provide means in association with the tank for circulating the 'liquid developer past the films in the tank. This means is of such a nature that it will prevent the accumulation of any air bubbles on the films which would interfere with proper development of the films.

Various other objects and advantages will be apparent from the drawing and the following description.

The preferred embodiment of my invention is illustrated in the accompanying drawing wherein similar characters of reference designate corresponding parts and whereinr;

. Figure a perspective view, partly cut away,

showing aj'illm-developing tank constructed in ac- 1 cordance with my invention. 5

;-Flg'ure 2 is a vertical section taken through the "structure illustrated in Figure 1.

Figure 3 is a detail partly in section and partly ii -perspective illustrating a combined timing device. and driving means for the liquid circulating device.

' With reference to the drawing and, particularly, to Figures 1 and 2, I have illustrated a film- 'developing tank'made in accordance withmy in vention. This film-developing tank comprises a other suitable material. A container 2 for the developing liquid is mounted on the base I, in the mannerillustrated. This container is con;- v structed of transparent material. The material 20 may be glass, 9. clear plastic or any other clear and transparent acid-resisting material. It may be in'one piece. as illustrated in the drawing, vor may be .made of several sections secured together in a suitable manner. The tank is comparatively tall so that films 3 of the roll-film type may be suspended therein .and, during the process of development, they will be constantly submerged in the developing fluid.

The bottom of the tank is closed and the top is open as indicated. However, I provide a hinged cover or lid 4 for closing the top, of the tank. This cover is adapted to keep dust out of the tank. The lid is preferably a tight-fitting lid which serves to make the container air-tight so that the developing fluid may be kept in the container for long periods, it desired, and will retain its strength for a longer period than if the container were not air-tight.

In order to suspend the films 3. in the tank, the upper edge of the tank is provided with a series of oppositely disposed notches} formed therein. These notches receive rods 6 which may be of wood,.metal, glass, or other "suitable material. The films may be suspended'trom these rods by means of clips I. Thelower ends of the films also have clips v8 secured thereto, which serveas weights to maintain the film vertically suspended in the tank. Thus, the films will be suspended in spaced relationship in the tank and 50 will be .vertically disposed. Because all of the sides of the tank are made of transparent material, the film may be viewed without removing it from the tank. Thus. the progress of the development may be noted from time to time with- 55 out removing the films from the tank through the use of safe light" moved up and down back of the tank.

In order to provide means for effectively circulating the liquid developer past the films suspended in the tank, a device of the type illustrated in Figures 1 and 2 may be mounted on the tank. This device comprises a vertically disposed tube 9 which is secured to one of the side walls of the container 2 and on the exterior thereof. A member M for developing fluid to enter the container 2 leads from the lower end of this tube into the container adjacent the bottom thereof. A member H for developing fluid to leave the container 2 leads from the container into the upper end of the tube 9. The outlet II is disposed adjacent the upper end of the container. A helical or spiral screw member I2 is rotatably supported within the tube 9 and in close association with the wall thereof. The screw member I2 is driven by a motor unit 13 which is connected to the upper end of the screw by a worm and gear drive I. The inlet member ID has a fan-shaped nozzle member I5 associated therewith.

In the operation of this circulating device, when the unit I3 is operated, it will drive the screw I2 in the proper direction. This will force the liquid developer from the tube 9 and through the inlet l0 into the bottom of the container. The fan-shaped nozzle I 5 will serve to widely distribute the liquid forced into the container 2.

The container 2 will always be full of the developing liquid during the developing operation. At the same time, the liquid is forced into the lower end of the container 2 through the inlet member ID, the liquid will be withdrawn from the upper end of the container through the outlet II and back into the tube 9. Thus, there will be a constant circulation of liquid from the bottom to the top of the container.

Thus, vertical circulation of the developing liquid from the bottom to the top of the container past the films is provided. This type of circulation will prevent the accumulation of any air bubbles on the films which would interfere with the proper development of the films and would result in bare spots or defects on the finished films which would require retouching of the negatives. It also provides for even development, if desired. The direction of circulation could be reversed, that is, it would circulate from the top towards the bottom of the container although I prefer to circulate it from the bottom to the top of the container.

The tank may be used in a dark room and, from time to time, the development of the films may be observed by using a safe light and without removing the films from the tank. However, in some instances, it may be desirable to provide a light-proof cover for covering the entire device while the developing operation is in progress. For example, it may be desirable to have the developing room illuminated so that the user of the device could be performing some other task while the development is occurring. For this purpose, I provide a light-proof cover H; which is adapted to cover completely the container 2. This cover I6 is made of a suitable material through which light will not pass and takes the form of a hood with its lower end only open and which is adapted to be put over the container 2. The lower edge of this member 16 will rest on a shoulder or ledge l1 formed on the base. The inner surface of the member l6 adjacent its lower edge cooperates with a vertical surface l8 formed on the base which will prevent displacement of the cover It on the base. The cover is sufficiently large to cover the circulating device provided on the side of the container.

The bottom of the container is provided with an outlet l9 by means of which the liquid developer may be removed from the container. This outlet is under the control of an adjustable valve 20. A removable screen 2| is preferably associated with the outlet so that as the liquid developer is drained from the container it is strained. The liquid developer may then be used over again.

In Figure 3, I illustrate the unit l3 which consists of a combined timing device and operating motor for driving the screw l2 of Figures 1 and 2. This timing device comprises a housing 25 in which a sleeve member 26 is rotatably mounted. This sleeve 28 has a worm 21 thereon which meshes with a worm gear 28 keyed to the upper end of the screw I2. The forward end of the sleeve 26 carries a disk-likemember 29 having ratchet teeth 30 formed on the periphery there-- 01. A spring-press pawl 3| contacts with these ratchet teeth. This pawl 3| is carried on the interior of a drum-like member 32. This member 32 has a clock face 33 on which the sleeve 26 is rotatably mounted. The shaft 34 is anchored to the housing 25 as at 34a so that it will not rotate. A spiral spring 35 is supported within the drum 32 and has its inner end secured to the stationary shaft 34 as at 38 and its outer end secured to the rotatable drum 32 as at 31.

In order to wind up the device to place the spring in tension, the drum member 32 is rotated counterclockwise relative to the housing 25 and the ratchet member 29. A pointer 38 is supported by the housing 25 and cooperates with the-clock face 33 on member 32. Turning the member 32 relative to the member 29 will cause the pawl 3| to ride over the ratchet teeth 30. This will also wind up the spring 35 since one end thereof is anchored to the stationary shaft 34 while the other end is anchored to the member 32 which is rotatably mounted on shaft 34. The member 32 is rotated until the pointer 38 is adjacent to the time-indication selected. This time-indication will indicate the time required for the device to unwind. If the member 32 is now released, the spring 35 will rotate it in a clockwise direction. The pawl 3| will engage one of the ratchet teeth and, consequently, will rotate member 29 with member 32. Since member 29 carries the worm 21, the screw l2 will be driven. Rotation of the screw will continue until the spring 35 is completely unwound.

Thus, this device serves to time the developing operation as well as to drive the circulating means. The device will be set to run for a predetermined period which will be suitable for the developing operation. When it is completely unwound, this will indicate that the film has had suilicient time to be developed. If desired, the timing device may be arranged to actuate a signal which will indicate when the developing operation is completed.

It will be apparent from the description above that I have provided a film-developing tank having many advantages. It is particularly useful for developing roll film, but it is not limited thereto. Because of the tank being made of transparent material, the progress of development of the films may be noted without removing them therefrom. It will be noted that I have provided effective means for circulating the liquid developer in the tank and this circulation is carried on in such a manner that there will be no danger of air bubbles accumulating on the film. Although I have only referred to photographic film, it is to be understood that my invention may be used for developing other types of film, such as X-ray film, et cetera.

As previously described, the film-developing tank is preferably of clear transparent material. It may, however, be made of a safe" glass or plastic. This glass or plastic may have orthochromatic or panchromatic qualities. It will keep the film in the tank from being light-logged ceive the developing liquid, the film being adapted to be supported vertically within the tank, said tank being provided with an inlet and an outlet adjacent its ends, a tube supported outside or said tank and having one end connected to said outlet and its opposite end connected to said inlet, and means disposed within said tube for forcing developing liquid contained in said tube from said tube through said inlet into the tank and for simultaneously withdrawing developing liquid from 6 said tank through said outlet and into said tube, said means comprising a rotatable screw member disposed within said tube, and spring-operated clock mechanism for rotating said screw member and for timing the developing operation.

2. A tank for use in developing photographic film or the like, said tank being adapted to receive the developing liquid, the film being adapted to be supported vertically within the tank, said tank being provided with an inlet and an outlet 15 adjacent its ends, a tube supported outside of said tank and having one end connected to said outlet and its opposite and connected to said inlet, means disposed within said tube for forcing developing liquid contained therein from said tube 20 through said inlet into the tank and for simultaneously withdrawing developing liquid from said tank through said outlet and into said tube, said means comprising a rotatable screw member disposed within said tube, and a combined timing 25 device and driving motor for driving said screw.

WALTER. B. MOORE. 

